This invention relates to a pattern defect inspection method for inspecting a defect in a repetitive pattern of an inspection object, a photomask manufacturing method for manufacturing a photomask by carrying out such a defect inspection, and a display device substrate manufacturing method for manufacturing a substrate for a display device (hereinafter also referred to as a “display device substrate”) using such a photomask.
For a display device substrate as an inspection object or a photomask, as an inspection object, used for manufacturing the display device substrate, it is necessary to inspect a defect in a pattern formed on the surface thereof. This defect in the pattern includes an error such that irregularity unintentionally takes place in regularly arranged unit patterns. This may also be called an irregularity defect and is generated due to some cause in the manufacturing process or the like.
If a defect occurred in a pattern of a photomask used in the manufacture of a display device, the defect is transferred to a pattern of a substrate for the display device. If the defect exists in the display device substrate, there is a possibility that display unevenness occurs, leading to a reduction in device performance.
Even when the foregoing defect in the pattern of the display device substrate or the photomask cannot be detected in a shape inspection of individual unit patterns due to the fact that, normally, fine defects are regularly arranged, the entire region including the defects is observed to be different from other portions. Therefore, the defect inspection is mainly performed by an appearance inspection such as an oblique light inspection by visual observation.
However, since there is a problem that this visual inspection causes variation in inspection results depending on an operator, there has been a demand for automation of a defect inspection using a defect inspection apparatus.
As an apparatus that automates a visual oblique light inspection, there is, for example, a macro inspection apparatus for a substrate for a semiconductor device manufactured by a semiconductor wafer. For example, Japanese Unexamined Patent Application Publication (JP-A) No. H09-329555 discloses an apparatus comprising a light source adapted to irradiate a light with a predetermined wavelength onto a periodic structure (repetitive pattern) formed on the surface of a semiconductor wafer, a camera adapted to receive diffracted light from the surface of the wafer, and detection means for detecting a defect by comparing image data captured by the camera with defectless reference data. This macro inspection apparatus captures the entire surface of the wafer in a single field of view, thereby inspecting a surface defect in the periodic structure on the surface of the wafer caused by a focus offset, a defocus due to variation in upper and lower positions of the wafer by the presence of dust (particles) on the bottom surface of the wafer, or a developing, etching, or stripping process of the wafer.